Current Detector

Abstract

To provide a current detection device including a shunt resistor capable of reducing a resistance temperature coefficient with a simple structure.SOLUTION: A current detection device 30 comprises a resistive element 5 and a pair of electrodes 6 and 7. The current detection device 30 is formed with a pair of first slits 16 and 17 and a pair of second slits 26 and 27. The first slits 16 and 17 are formed so as to be overlapped with the electrodes 6 and 7 and a resistive element 5 in a first direction. The second slits 26 and 27 are formed on the electrodes 6 and 7 in a second direction. On the electrodes 6 and 7, detection regions 24a and 25a are sectionalized by the first slits 16 and 17, the second slits 26 and 27, and contact surfaces 6a and 7a at least partially contacted with the resistive element 5. The electrodes 6 and 7 further have voltage detectors 20 and 21 arranged in the detection regions 24a and 25a.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a current detection device, and more particularly to a current detection device using a shunt resistor. [Background technology]

[0002] Shunt resistors are widely used for current detection. Such shunt resistors include a resistive body and electrodes joined to both ends of the resistive body. In general, the resistive body is made of a resistive alloy such as a copper-nickel alloy, a copper-manganese alloy, an iron-chromium alloy, or a nickel-chromium alloy, and the electrodes are made of a highly conductive metal such as copper. The electrodes are provided with a voltage detection section, and a conductor (e.g., an aluminum wire) is connected to the voltage detection section to detect the voltage generated at both ends of the resistive body. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-90205 A Summary of the Invention [Problem to be solved by the invention]

[0004] In a shunt resistor, the temperature coefficient of resistance (TCR) is important to enable current detection under conditions where the influence of temperature fluctuations is small. The temperature coefficient of resistance is an index that indicates the rate of change in resistance value due to temperature. Therefore, the present invention aims to provide a current detection device using a shunt resistor that can reduce the temperature coefficient of resistance with a simple structure. [Means for solving the problem]

[0005] In one embodiment, a current detection device for use in current detection is provided, comprising a resistor and a pair of electrodes connected to both ends of the resistor, wherein the current detection device has a pair of first slits and a pair of second slits connected to the pair of first slits, each of the first slits is formed so as to span each electrode and the resistor along a first direction which is the arrangement direction of the pair of electrodes, and each of the second slits is formed in each of the electrodes along a second direction which is perpendicular to the first direction, each of the electrodes has a detection area defined by each of the first slits, each of the second slits, and a contact surface at least a portion of which contacts the resistor, and each of the electrodes further has a voltage detection unit arranged in the detection area.

[0006] In one aspect, the voltage detection portion is disposed closer to the resistor than the center of the detection area. In one embodiment, the detection region protrudes beyond the resistor in a thickness direction of the current detection device. In one embodiment, the voltage detection portion is disposed adjacent to the contact surface and each of the first slits. In one aspect, the current detection device further includes a wiring board, the wiring board including a detection member connected to the voltage detection portion. In one embodiment, the pair of first slits are connected to each other. Effect of the Invention

[0007] The temperature coefficient of resistance can be reduced by disposing the voltage detection portion in a detection region defined by the first slit, the second slit, and a contact surface at least a portion of which is in contact with the resistor. [Brief description of the drawings]

[0008] [Figure 1] 1 is a perspective view showing an embodiment of a current detection device as a shunt type current detection device. [Diagram 2] FIG. 2 is a side view of the current detection device shown in FIG. [Diagram 3]FIG. 2 is a partially enlarged view of the shunt resistor, showing the shunt resistor as viewed from above. [Figure 4] FIG. 13 is a schematic diagram showing another embodiment of the current detection device. [Diagram 5] FIG. 13 is a schematic diagram showing another embodiment of the current detection device. [Figure 6] FIG. 13 is a schematic diagram showing another embodiment of the current detection device. [Figure 7] FIG. 13 is a schematic diagram showing another embodiment of the current detection device. [Figure 8] FIG. 13 is a schematic diagram showing another embodiment of the current detection device. [Figure 9] FIG. 13 is a schematic diagram showing another embodiment of the current detection device. [Figure 10] FIG. 11 is a perspective view showing still another embodiment of a current detection device. [Figure 11] FIG. 2 is a partially enlarged view of the current detection device. [Figure 12] FIG. 13 is a schematic diagram showing still another embodiment of the current detection device. [Figure 13] FIG. 13 is a schematic diagram showing still another embodiment of the current detection device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings described below, the same or corresponding components are denoted by the same reference numerals, and duplicated descriptions will be omitted. In the multiple embodiments described below, the configuration of one embodiment that is not particularly described is the same as the other embodiments, so duplicated descriptions will be omitted.

[0010] FIG. 1 is a perspective view showing an embodiment of a current detection device 30 as a shunt type current detection device, and FIG. 2 is a side view of the current detection device 30 shown in FIG. 1. In FIG. 2, a part of the current detection device 30 is omitted. In this embodiment, the current detection device 30 includes a shunt resistor 1. In other words, the current detection device 30 of this embodiment is the shunt resistor 1 itself. As shown in FIG. 1 and FIG. 2, the shunt resistor 1 includes a resistor 5 made of a resistive alloy plate material having a predetermined thickness and width, and a pair of electrodes 6, 7 made of a highly conductive metal connected to both ends (i.e., both connection faces) 5a, 5b of the resistor 5 in the first direction. The electrode 6 has a contact surface 6a at least a part of which contacts one end (one connection face) 5a of the resistor 5, and the electrode 7 has a contact surface 7a at least a part of which contacts the other end (the other connection face) 5b of the resistor 5. The electrodes 6, 7 are formed with fastening holes 8, 9 for fixing the shunt resistor 1 with screws or the like.

[0011] The first direction is the length direction of the current detection device 30, i.e., the length direction of the shunt resistor 1, and is the direction in which the electrode 6, resistor 5, and electrode 7 are arranged in this order. In other words, the first direction is the direction in which a current flows. A direction perpendicular to the first direction is the second direction. The second direction is the width direction of the current detection device 30, i.e., the width direction of the shunt resistor 1. As shown in Figures 1 and 2, the electrodes 6 and 7 have the same structure and are arranged symmetrically with respect to the resistor 5.

[0012] Both ends 5a, 5b of the resistor 5 are connected (joined) to the electrodes 6, 7, respectively, by means of welding (for example, electron beam welding, laser beam welding, or brazing). Examples of materials for the resistor 5 include low-resistance alloy materials such as Cu-Mn alloys and Ni-Cr alloys. Examples of materials for the electrodes 6, 7 include copper (Cu). Cu-Mn alloys and Ni-Cr alloys have higher resistivity than copper.

[0013] As shown in FIG. 1 and FIG. 2, in this embodiment, the thickness of the electrodes 6, 7 is thicker than the thickness of the resistor 5. As shown in FIG. 2, the back surfaces of the electrodes 6, 7 and the back surface of the resistor 5 are on the same plane. The surfaces 6b, 7b of the electrodes 6, 7 are located higher than the surface 5c of the resistor 5 in the thickness direction of the current detection device 30 (shunt resistor 1). The thickness direction of the current detection device 30 (shunt resistor 1) is a direction perpendicular to both the first direction and the second direction. A step 18 is formed by the surface 6b of the electrode 6, the contact surface 6a, and the surface 5c of the resistor 5, and a step 19 is formed by the surface 7b of the electrode 7, the contact surface 7a, and the surface 5c of the resistor 5. A space SP is formed by the steps 18, 19, and the surface 5c.

[0014] 1, a pair of slits 12, 13 are formed in the shunt resistor 1 of the current detection device 30. The slit 12 includes a first slit 16 and a second slit 26, and the slit 13 includes a first slit 17 and a second slit 27. That is, the shunt resistor 1 of the current detection device 30 is formed with a pair of first slits 16, 17 and a pair of second slits 26, 27.

[0015] 3 is a partial enlarged view of the shunt resistor 1, and is a view of the shunt resistor 1 seen from above. As shown in FIG. 3, the first slit 16 is formed so as to span the electrode 6 and the resistor 5 along the first direction, and the second slit 26 is formed in the electrode 6 along the second direction. The first slit 17 is formed so as to span the electrode 7 and the resistor 5 along the first direction, and the second slit 27 is formed in the electrode 7 along the second direction. Specifically, the first slit 16 is formed from the electrode 6 to a part of the resistor 5 along the first direction, and the first slit 17 is formed from the electrode 7 to a part of the resistor 5 along the first direction.

[0016] The second slits 26 and 27 are connected to the first slits 16 and 17, respectively. Specifically, one ends of the first slits 16 and 17 are connected to the centers of the second slits 26 and 27, respectively. The slits 12 and 13 penetrate the shunt resistor 1 in the thickness direction, and have a convex shape toward the resistor 5 when the shunt resistor 1 is viewed from above.

[0017] 3, the electrode 6 is defined into detection regions 24a and 24b by the first slit 16, the second slit 26, and the contact surface 6a, and the electrode 7 is defined into detection regions 25a and 25b by the first slit 17, the second slit 27, and the contact surface 7a. The detection regions 24a and 24b are formed on the surface 6b of the electrode 6, and the detection regions 25a and 25b are formed on the surface 7b of the electrode 7. The detection regions 24a, 24b, 25a, and 25b protrude beyond the resistor 5 in the thickness direction of the current detection device 30 (the thickness direction of the shunt resistor 1).

[0018] 3, the electrodes 6 and 7 have voltage detection units 20 and 21, respectively, for measuring the voltage (voltage of the resistor 5) generated across both ends 5a and 5b of the resistor 5. The voltage detection unit 20 is disposed on the detection area 24a, and the voltage detection unit 21 is disposed on the detection area 25a. In one embodiment, the voltage detection units 20 and 21 may be disposed on the detection areas 24b and 25b, respectively.

[0019] The current flows through the shunt resistor 1, avoiding the slits 12 and 13. Therefore, potential distribution is unlikely to occur in the detection regions 24a, 24b, 25a, and 25b. Therefore, by arranging the voltage detection units 20 and 21 in the detection regions 24a and 25a (or the detection regions 24b and 25b), the resistance temperature coefficient of the shunt resistor 1 can be reduced. In other words, by extracting a voltage from the voltage detection units 20 and 21 arranged in the detection regions 24a and 25a (or the detection regions 24b and 25b), it is possible to perform voltage measurement with a small resistance temperature coefficient, and stable current detection can be performed.

[0020] If the first slits 16, 17 were formed only on the electrodes 6, 7 with a gap between them and the resistor 5, the current would concentrate in the gap between the first slits 16, 17 and the resistor 5, and the potential distribution would be large in the area near the first slits 16, 17 and the resistor 5. Therefore, it would be impossible to create an area where the potential distribution is unlikely to occur as in this embodiment. In addition, if the slits 12, 13 were formed in a location away from the resistor 5 to avoid such current concentration, the detection area would be away from the resistor 5, and the voltage measurement would be affected by the temperature characteristics of the resistance value of the material (electrode material) of the electrodes 6, 7. In order to measure the voltage of the resistor 5 while reducing the influence of the temperature characteristics of the electrode material, it is desirable to take out the voltage from a position close to the resistor 5.

[0021] On the other hand, in this embodiment, the first slit 16 is formed so as to overlap the electrode 6 and the resistor 5, and the first slit 17 is formed so as to overlap the electrode 7 and the resistor 5. This makes it possible to avoid the above-mentioned current concentration and eliminate areas where the potential distribution becomes large. In addition, since a position close to the resistor 5 can be set as the voltage detection position (position of the voltage detection units 20 and 21), it becomes possible to perform voltage measurement that is less affected by the temperature characteristics of the electrode material. As a result, the resistance temperature coefficient of the shunt resistor 1 can be reduced.

[0022] In addition, since the first slits 16, 17 and the contact surfaces 6a, 7a form an edge portion, the voltage detection position (the position of the voltage detection units 20, 21) can be aligned using this edge portion as a base point. This makes it possible to reduce voltage measurement errors due to the voltage detection position and to identify a voltage detection position with good temperature characteristics, thereby enabling stable voltage measurement. In addition, by controlling the voltage detection position (the position of the voltage detection units 20, 21), it becomes possible to correct the temperature characteristics for material characteristics and manufacturing variations.

[0023] In this embodiment, the slits 12 and 13 have a convex shape, but in one embodiment, the corners of the slits 12 and 13 may have an R-surface or a C-surface.

[0024] In this embodiment, the voltage detection units 20 and 21 are disposed closer to the resistor 5 than the centers (center lines CL1 and CL2) of the detection areas 24a and 25a in the first direction. In one embodiment, the voltage detection units 20 and 21 may be disposed closer to the resistor 5 than the centers (center lines CL1 and CL2) of the detection areas 24b and 25b in the first direction. This makes it possible to further reduce the effect of the temperature characteristics of the resistance value of the electrode material, and to more accurately measure the voltage of the resistor 5.

[0025] More specifically, the voltage detection unit 20 is disposed adjacent to the contact surface 6a and the side wall 16a of the first slit 16, and the voltage detection unit 21 is disposed adjacent to the contact surface 7a and the side wall 17a of the first slit 17. In one embodiment, the voltage detection unit 20 may be disposed adjacent to the contact surface 6a and the side wall 16b of the first slit 16, and the voltage detection unit 21 may be disposed adjacent to the contact surface 7a and the side wall 17b of the first slit 17. This makes it possible to further reduce the influence of the temperature characteristics of the resistance value of the electrode material, and to more accurately measure the voltage of the resistor 5.

[0026] Further, in one embodiment, as shown in Fig. 4, the electrodes 6, 7 may further include voltage detection units 22, 23 for measuring the voltage of the resistor 5. The voltage detection unit 22 is disposed on the detection area 24b, and the voltage detection unit 23 is disposed on the detection area 25b. Specifically, the voltage detection units 22, 23 are disposed closer to the resistor 5 than the centers (center lines CL1, CL2) of the detection areas 24b, 25b in the first direction. More specifically, the voltage detection unit 22 is disposed adjacent to the contact surface 6a and the side wall 16b of the first slit 16, and the voltage detection unit 23 is disposed adjacent to the contact surface 7a and the side wall 17b of the first slit 17.

[0027] Voltage detection unit 20 and voltage detection unit 22 are at the same potential, and voltage detection unit 21 and voltage detection unit 23 are at the same potential. By extracting voltage from two pairs of voltage detection units, it is possible to suppress fluctuations in potential due to the current path after the voltage is extracted from shunt resistor 1.

[0028] In one embodiment, the shunt resistor 1 is formed by shaping a long joint material consisting of a plate-shaped resistor and multiple copper plates joined to both ends of the resistor using a die, wire cutting, etc. In one embodiment, the slits 12 and 13 are formed by punching the shunt resistor 1 with a die or by shaping the shunt resistor 1 using wire cutting. Furthermore, in one embodiment, the TCR characteristic function can be controlled by adjusting the shapes of the slits 12 and 13.

[0029] FIG. 5 is a schematic diagram showing another embodiment of the current detection device 30. In FIG. 5, a part of the current detection device 30 is omitted. The configuration of this embodiment that is not particularly described is the same as the embodiment described with reference to FIG. 1 to FIG. 4, so the duplicated description will be omitted. As shown in FIG. 5, the current detection device 30 of this embodiment includes a shunt resistor 1 and a wiring board 31. The wiring board 31 includes detection members 36a and 36b. Wirings 40 and 41 for transmitting a voltage signal (voltage of the resistor 5) from the shunt resistor 1 are formed on the surface of the board body 33 of the wiring board 31, and the detection members 36a and 36b are connected to the wirings 40 and 41 through via holes 38a and 38b.

[0030] The detection members 36a and 36b are connected to the voltage detection units 20 and 21, respectively. An example of the detection members 36a and 36b is a metal pad formed by patterning copper foil. The detection members 36a and 36b are connected to the voltage detection units 20 and 21 across the steps 18 and 19 (so as to cover the contact surfaces 6a and 7a). The connection between the voltage detection units 20 and 21 and the wiring 40 and 41 of the wiring board 31 may be made using a metal lead frame (a plate-shaped conductive material) or a wire instead of the detection members 36a and 36b.

[0031] As described above, the shunt resistor 1 of this embodiment has the steps 18, 19, and the detection regions 24a, 24b, 25a, 25b protrude further than the resistor 5 in the thickness direction of the shunt resistor 1. This allows the detection members 36a, 36b to be disposed across the steps 18, 19. With this configuration, the voltage detection position can be brought closer to the resistor 5. As a result, the voltage of the resistor 5 can be measured with higher accuracy. In addition, the steps 18, 19 prevent the detection members 36a, 36b from contacting the resistor 5.

[0032] As described above, the resistor 5 is connected to the electrodes 6, 7 by means of welding or the like. Therefore, unevenness occurs at the joints between the resistor 5 and the electrodes 6, 7 due to welding marks. However, in this embodiment, the shunt resistor 1 has the steps 18, 19, so that the detection members 36a, 36b can be connected across the steps 18, 19 without being affected by the welding marks. In addition, a space SP is formed above the resistor 5, so that the heat generated by the resistor 5 can be prevented from being directly transmitted to the wiring board 31.

[0033] In one embodiment, as shown in Fig. 6, the wiring board 31 may include four detection members 36a, 36b, 36c, and 36d connected to the voltage detection units 20, 21, 22, and 23 (see Fig. 4), respectively. Via holes 38a, 38b, 38c, and 38d connected to wiring (not shown) are connected to the four detection members 36a, 36b, 36c, and 36d, respectively. In Fig. 6, the board body 33 is omitted from illustration. In this embodiment, the detection members 36a, 36b, 36c, and 36d are also arranged straddling the steps 18 and 19.

[0034] Fig. 7 is a perspective view showing still another embodiment of the current detection device 30. The configuration of this embodiment not specifically described is the same as that of the embodiment described with reference to Figs. 1 to 4, and therefore the duplicated description will be omitted. In this embodiment, one ends of the first slits 16 and 17 are connected to one ends of the second slits 26 and 27, respectively. In other words, the slits 12 and 13 have an L-shape when the shunt resistor 1 is viewed from above.

[0035] In the electrode 6, a detection area 24a is defined by a first slit 16, a second slit 26, and a contact surface 6a, and in the electrode 7, a detection area 25a is defined by a first slit 17, a second slit 27, and a contact surface 7a. In this embodiment, too, the effects described with reference to Figures 1 to 4 can be achieved, and the embodiment described with reference to Figures 5 and 6 can also be applied to this embodiment.

[0036] FIG. 8 is a perspective view showing yet another embodiment of the current detection device 30. The configuration of this embodiment that is not particularly described is the same as the embodiment described with reference to FIG. 7, so the overlapping description will be omitted. In this embodiment, the position of the first slit 16 in the second direction is different from the position of the first slit 17 in the second direction, and the second slits 26 and 27 extend in opposite directions. That is, the orientation of the L-shaped shapes of the slits 12 and 13 is inverted vertically and horizontally when the shunt resistor 1 is viewed from above. This embodiment can also achieve the effects described with reference to FIGS. 1 to 4, and the embodiments described with reference to FIGS. 5 and 6 can also be applied to this embodiment.

[0037] FIG. 9 is a perspective view showing still another embodiment of the current detection device 30. In FIG. 9, a part of the current detection device 30 is omitted from illustration. Since the configuration of this embodiment that is not particularly described is the same as the embodiment described with reference to FIG. 4, the duplicated description will be omitted. The current detection device 30 of this embodiment includes a shunt resistor 1 and voltage detection terminals 50, 51, 52, and 53. The shunt resistor 1 of this embodiment differs from the shunt resistor 1 of FIG. 4 in that it does not have steps 18 and 19. That is, in this embodiment, the electrodes 6 and 7 and the resistor 5 have the same thickness.

[0038] Voltage detection terminals 50, 51, 52, and 53 are provided on voltage detection units 20, 21, 22, and 23, respectively. One example of the voltage detection terminals 50, 51, 52, and 53 is a pin terminal. This embodiment can also achieve the effects described with reference to Figures 1 to 4, and the embodiment described with reference to Figures 7 and 8 can also be applied to this embodiment.

[0039] Fig. 10 is a perspective view showing still another embodiment of the current detection device 30, and Fig. 11 is a partially enlarged view of the current detection device 30. Fig. 11 is a view of the current detection device 30 as viewed from above. The configuration of this embodiment that is not particularly described is the same as that of the embodiment described with reference to Figures 1 to 3, and therefore the duplicated description will be omitted. In Figures 10 and 11, illustration of a part of the current detection device 30 is omitted.

[0040] In this embodiment, the first slit 16 and the first slit 17 are connected to each other. In other words, it can be said that the first slit 16 is formed from the electrode 6 to the electrode 7, and the second slits 26, 27 are connected to both ends of the first slit 16. It can also be said that the first slit 17 is formed from the electrode 7 to the electrode 6, and the second slits 26, 27 are connected to both ends of the first slit 17.

[0041] In one embodiment, as shown in FIG. 12, the electrode 6 may further include a voltage detection unit 22 arranged on the detection area 24b, and the electrode 7 may further include a voltage detection unit 23 arranged on the detection area 25b. In this embodiment, the voltage is detected from two pairs of voltage detection units. Furthermore, in one embodiment, as shown in FIG. 13, the electrode 6 may include a voltage detection unit 20 arranged on the detection area 24a, and the electrode 7 may include a voltage detection unit 23 arranged on the detection area 25b. In this embodiment, the voltage of the resistor 5 is measured on a diagonal line sandwiching the first slits 16 and 17.

[0042] The embodiment described with reference to Figures 10 to 13 can also achieve the same effects as those described with reference to Figures 1 to 4. The embodiment described with reference to Figures 5 and 6 and the voltage detection terminals 50, 51, 52, and 53 described with reference to Figure 9 can also be applied to the embodiment described with reference to Figures 10 to 13.

[0043] The above-described embodiments have been described for the purpose of enabling a person having ordinary skill in the art to practice the present invention. Various modifications of the above-described embodiments are naturally possible for a person skilled in the art, and the technical idea of ​​the present invention can be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but is to be interpreted in the broadest scope according to the technical idea defined by the claims. [Explanation of symbols]

[0044] 1 Shunt resistor 5 Resistor 5a, 5b both ends (connection surfaces on both sides) 5c surface 6,7 electrodes 6a,7a Contact surface 6b,7b surface 8,9 Fastening holes 12,13 Slit 16,17 First slit 16a,16b,17a,17b side wall 18,19 Steps 20, 21, 22, 23 Voltage detection section 24a, 24b, 25a, 25b Detection area 26,27 Second slit 30 Current detection device 31 Wiring board 33 Board body 36a, 36b, 36c, 36d Detection members 38a, 38b, 38c, 38d Via holes 40,41 Wiring 50, 51, 52, 53 Voltage detection terminals

Claims

1. A current detection device used for current detection, A resistor; A pair of electrodes connected to both ends of the resistor, The current detection device includes a pair of first slits and a pair of second slits connected to the pair of first slits, Each of the first slits is formed so as to extend across each of the electrodes and the resistor along a first direction that is a direction in which the pair of electrodes are arranged, Each second slit is formed in each electrode along a second direction perpendicular to the first direction, In each of the electrodes, a detection area is defined by the first slits, the second slits, and a contact surface at least a part of which is in contact with the resistor, Each of the electrodes further includes a voltage detection portion disposed in the detection region, the detection region between the contact surface and the second slit is formed by a surface of the electrode, A current detection device, wherein each of the first slits is embedded in a portion of the resistor along the first direction.

2. The current detection device according to claim 1 , wherein the voltage detection portion is disposed closer to the resistor than a center of the detection area.

3. The current detection device according to claim 1 , wherein the detection region protrudes beyond the resistor in a thickness direction of the current detection device.

4. The current detection device according to claim 1 , wherein the voltage detection portion is disposed adjacent to the contact surface and each of the first slits.

5. A wiring board is further provided, The current detection device according to claim 1 , wherein the wiring board includes a detection member connected to the voltage detection portion.

6. A current detection device used for current detection, comprising: A resistor; A pair of electrodes connected to both ends of the resistor, The current detection device includes a first slit and a pair of second slits connected to the first slits, The first slit is formed from one electrode to the other electrode along a first direction which is an arrangement direction of the pair of electrodes, Each second slit is formed in each electrode along a second direction perpendicular to the first direction, In each of the electrodes, a detection area is defined by the first slit, each of the second slits, and a contact surface at least a part of which is in contact with the resistor, A current detection device, wherein each of the electrodes further includes a voltage detection portion disposed in the detection region.

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